Grease for mechanical lubrication



March 17; 1925- JMCKEE ET AL GREASE FOR MECHANICAL LUBRICATION Filed July 29, 1921 A Jmes MCA/Ce 713 Patented Mar. `17, 1.92.5.

UNITED STATES .PATENT ori-leeg JAMES MQKEE, on CHESTER, ANn SAMUEL E. EcxEn'r, oE'nEvoN, PENNSYLVANIA', AssIGNoEs To SUN oIL COMPANY, or PHILADELPHIA, PENNSYLVANIA, A con- '.PORATION OF NEW JERSEY.

GREA/SE FOR MECHANICAL LUBBICATION.

Application mea Vmy 29, 1921. serial No. 488,271.

a grease for mechanical lubrication that, in`

its combined qualities, is superiorto ordinary grease and more economical of` manufacture. Inasmuch as the manufacture of the grease seems to involve the employment of a process substantially different from thatI used .in the manufacture of ordinary grease, We shall herein describe not only-its composition but also the method by which it has been successfully manufactured von a 25 commercial scale. Such process, however, is

not herein claimed, but forms the subjectmatter of a separate application filed by us July Q9, 1921, Serial No. 488,272.` The composition forming the subject-matter of the 3o present application is not, therefore, limited to any particular process of manufacture. The invention comprises an admixture of unsaponiiable mineral oil, a saponied fatty acid derivative from mineral oil of the character hereinafter described, and a' saponified animal or vegetable oil; the product being a grease -of desirable density which is neutral in reaction, free from moisture, that does not decompose and preserves its lubris 4eating qualities during and after exposure to a temperature in excess of the boiling point of water, that preserves its viscosity at a temperature of thirty degrees or more below zero l'Fahrenheit that doesnot oxi-v f dize, and that does not leave ahard' or soapy residue after prolonged exposure'. y

The preferred totalv proportion of the saponified ingredients is not necessarily different from that characteristic .ofordinary greases, although preferably such vproportion slightly exceeds that of the lsaponifed vegetable or animal oil used in ordinary greases. Due to the fact that a saponified mineral oil derivative is used in partial substitution for a saponified animal .or vegetable 'oil and .that such derivative is substantially cheaper than any ordinarily available vegetable or animal oil, a material saving in cost of production is effected. There is no practical minimum limit to the per-` centage of vegetable or animal oil and we have succeeded inproducing vefficient greaseswhich contain no ingredient whatever of vegetable or animal oil; but such greases do n', have the density that is ordinarily dea e.- ,f Y

The Saponiable mineral oil derivatives that we have found available `are the products known as Maitland fattyacids, which are water-insoluble, practically odorless, do not become rancid, contain a-verylow percentage of sulfur, usually much less than one per cent, and when saponified being soluble in all proportions with water and wholly or partially soluble in mineral oil and adapt-l ed to undergo the character of hydrolytic decomposition that occurs with soaps derived from animal and vegetable oil.

The Maitland product that we prefer to use is a liquid and whenl saponified entirely soluble in all proportions with mineral oil. It is preparcdby distilling from crude peltroleum a relatively heavyvdistillate adapt- .ed for lubricating oilv stock, treating the same with a mineral acid preferably s'ulphuric acid and separating out the precipitated sludge with a large p art of the acid,

treating the remaining body of acid-containing oil -with an alkali, separating out the precipitated soap and alkaline salt water,-

decomposing the soap lwith a relatively weak solution of a mineral acid and eliminating most of the salt water.

Another Maitland product that may be less l preferably used is solid `at ordinary temperasoy tures and .when saponified only partially Sol-` uble in mineral oil. It is made by Subjecty ing the sludge produced in the process'aboveV described to a mechanical mastication and4 concurrent washing with hot water that is continuously freshly supplied and 'lowS` llp-r throuoh thev mass of the sludge ,and

wardly o continuously outflows at 'the top; l 1

` These saponifiable` derivatives `from min#` eral oil and certain processes of making them are more specifically described in the y age of which will vary more or less.

Maitland Patents No. 1,425,882, No.v1,425, 883, No. 1,425,884 and No. 1,425,885,.all issued August 15, 1922. Patents No. 1,425,- 882 and No. 1,425,884 set forth the Maitland product specified above as preferable and the preferred process of making such'. product.

As statedin the specifications of atents No. 1,425,882 and No. 1,425,884, the saponified fatty aeids'produced by the process therein described are admixed with more proportions, herein specified for "Maitland fatty acids. We have herein specified the saponificationvalue of the Maitland fatty `acids that ive-have usually used, from which the preferable proportionsof the pure fatty acid can be readily calculated.

We have also found it advantageous, if not necessary, to manufacture the above saponifiable mineral oil derivative from av crude petroleum thatcontains not over a small proportion of parafline: The best results are. obtained from Gulf Coast crude,

which is free from parafline.

Our experiments with various vegetable and animal'oils lead us to believe that any saponifiable vegetable or animal oil is available; and in restricting the claims to a vege-` table oil it will be understood that we mean to include animal oil as an equivalent'. vAs examples of workable and satisfactory sa- 4ponifable non-mineral oils may be' mentioned tallow, horse oil, corn oil and castor oil.

'It is impossible to make very definite specifications of permissible percentages' of the ingredients mentioned, since it is desir-v able to make different kinds of grease, each of which is best adapted for aparticular liil'iricating field. These different kinds of grease require considerable variations in percentages of the several ingredients. In all eases, however, the proportion of unsaponi- `fiable mineral oil (which should'be refined lubricating oil) is several 'times' that of the other ingredients combined, while the pro-` portion ofthe saponifiable vegetable or ani-- mal oil maygvary froln a proportion much less than that of the 'saponifiable mineral oil derivative, to a proportion slightly, but not substantially, in excess of the proportion of the saponifiable mineral oil derivative.

Thus, ive have made greases containing from.

fifteen to twenty per cent of 50 saponification Maitland fatty acid with about one per cent of vegetable or animal oil; and on the other hand we have made greases containing approximately nine percent of 50 saponification of Maitland fatty acid and approximately as high as ten per cent ofvegetable or animal oil. y .Usually, however, when the' percentage of vegetable oi" animal oil `is reduced, the percentage of Maitland fatty acid is increased.

A typical grease that-gives excellent re sults comprises refined lubricating mineral oil, 50 saponification Maitland fattvV acid, 9%; and tallow, 6%. i

In the manufacture of our improved.. grease ive have. successfully used the lapparatus illustrated'in the accompanying drawing, which is an elevation, more or less diaf' gram'matic of the same. y The apparatus comprises a-grease still having a vapor stack or vent b and an Archiinedean screw agitator c. An outflow pipcl d, in which is interposed a pump e, connects with acooler and agitator. The cooler and agitator comprise a series of pipes f, througll which the grease is adapted to fioiv. Each pipe contains an Archimedean screw conveyor r] adapted to scrape theiinner walls -of thepipes. Each pipe is liacketed at l:

to provide a cold water circulation, adjacent jackets being connected to allow the water to flow from the jacket of one pipe to the jacket of another in the reverse direction i to the direction of flow of the grease. The greaseoutfiow pipe i from the cooler and agitator discharges into a water-jackcted agitator' and storage tank 7' equipped with paddles lc. A valve lmI regulates the out'- flow of the finished grease into packages A1. A motor lo'drives a main shaft p, from which the screw c in the still a, the sereivs (7 in the pipes f, andthe paddles k in the storage I tank j, are driven. i

Tlie still a is charged with the proper proportions of an unsaponifiable mineral oil. a saponifiable mineral oil derivative, and a vegetable or animal oil, together with a quantity of an alkali solution` preferably 30 Baum caustic soda, sufficient to neutralize all the saponifiable matter contained in the complete mixture. Usage will determinithe quantity of alkali required. An amount somewhat less than that so determined is first added and thereafter small proportions are added until, by successive titi-ations, the neutralizing point is found to be reached.

After .charging the still, the agitator c is put into motion and fire started under the still. The temperature of the stil1 is slowly1 raised to slightly above 212 degrees F., at which point the fire is held in check and the moisture resulting from the addition of the soda solution slowly driven of. While to boil over, it 'is advisable to hol Lasagne f the period during which the water is bein boiled o' and 'the reaction of alkali an saponifiable material is taking place ma1 be shortened to the actual time require to the still the still at the temperature specified for at least four hours in order to insure complete chem; ical combination.

After this first reaction and thedriving olf of all the Water, the mixture is raised rapidly to about 340 degrees F., after which the burners are turned olf and the mixture pumped out of the still into and through the, cooler and agitator.A Here the mixture is gradually cooled by the reverse flow of cold water through the pipe jackets h. The screws g assist in conveying the grease through the cooler and mix and agitate the grease, and by keeping the inner walls of the pipes f scraped clear ofgrease, considerab] facilitate transfer of heat.

y providing a suicient length of pipes boil off the Water Without causing1 and screws, the grease may be discharged from the agitator and cooler in a finished condition; but We refer .to discharge the grease into the `tang j and' there subject it to further agitation and mixing, the paddles lc also assisting in forcing the grease through the valved discharge into suitable containers.

The ultimate product vis entirely free from moisture. The expulsion of moisture does not, however, sacrilice any advantage whatever that results rom the Water-content that is presentv in ordinary grease composed of mineralfoil worked into a saponified animal or vegetable oil. The grease may be raised to a temperature substantially in excess of the boiling point of water and indeed to thel lashpoint of the` oil Without any. decomposition 'of the greaseand with no eii'ect upon it except to increase its Huidity. y Upon cooling'from such a higher temperature, the grease reverts to precisely the condition it was in before heating. Extreme .cold eiects viscosity only in degree. The density, of course, increases as the temperature is reduced, but it does not become hard, or anular or crystalline in texture; In fact, t egrease has a cold test equal, if

not superior, to the mi-neral oil or oils from7 Thus, a grease which it islargely made. made from a mineral oil having a cold test varying from thirty td forty degrees below zero F. will have the sameor a lower cold test. The grease, in its preferred embodispring shackle bolts and other .elements thataussah day Vof Ju1y, 1921..

ment, is neutral in reaction, itjbeing unnecessary, as inthe case of 'many greases, to carry itv Wellqon the alkaline side.f The greases do not oxidize and do not'leave. a

hard or soapy :residue when lft for a prolonged period in small oil passages or when maintained at a, hi h temperature for a long period.A This lqua ity is of especialfimpor-v tance when the grease is'used for lubricating are greased only periodically and then left exposed to the 'air forma prolonged time.

Having now fully described our invention, what We claimJ and desire to protect by lLetters Patent is: y

1. A grease for mechanical lubrication comprising an intimate mixture ofi-an unsaponiable mineralv oil, a saponiiedvegetable oil anda saponified'fatty acid vderivative of a mineral oil, which does not decompose during and after heatingy to a temperature above the boiling point of Water, Which ldoes not oxidize, and which has a cold test at least equal to that of its mineral oil constituent.

2. A grease in accordance With claim l which does not decompose when heated,y up to the flash pointof the grease.

3. A grease for mechanical lubrication comprising anintimate mixture of an unsaponifiable mineral oil in preponderating proportion, a saponiied vegetable oil and a l substantially neutral in reaction, which does not decompose during and after heating up to the lflash point of the grease'. which does not oxidize and does not leave a hard or soapy residue when left -for a prolonged period in a confined space or when `maintained at a high temperatiire' for a prolonged period and which retainsy viscosity when exposed to a temperature substantially below zero Fahrenheit. f

4. A grease for mechanical lubrication comprising a preponderati'ng proportion, not less than eighty per cent, of an unsaponiiiable lubricating m1ne1a l,-oil, and not over twenty per cent of al mixture of saponiied vegetable oil and'fasaponified fatty acid derivative from mineral In testimonyof :which-invention, we have hereunto set -our handsfat Phila.,

--JAMEsMKnn, ksalariat- 1a. ECKERT. 

